Low-temperature self-repairing water-based paint, preparation method and application thereof

Abstract

The application relates to the technical field of coatings, in particular to a low-temperature self-repairing water-based paint as well as a preparation method and application thereof. The low-temperature self-repairing water-based paint provided by the application has multiple core performances of stable film forming at a wide temperature range of 5-35 DEG C, rapid self-repairing at normal temperature of 10-30 DEG C, crack resistance and flexibility, wear resistance and corrosion resistance, meanwhile, the problems of high-temperature triggering, poor low-temperature fluidity, low repair efficiency, imbalance between flexibility and wear resistance, insufficient adhesion and the like of traditional self-repairing paints are avoided, the comprehensive performance is balanced and excellent, the preparation process is controllable, the construction adaptability is strong, and the low-temperature self-repairing water-based paint is suitable for the protection requirements of substrates in scenes such as metal corrosion prevention, building outer walls, cold chain equipment and the like which need normal-temperature rapid repair under no heating condition.

Description

Technical Field

[0001] This application relates to the field of coating technology, and in particular to a low-temperature self-healing waterborne coating, its preparation method, and its application. Background Technology

[0002] Water-based coatings represent a core direction in environmentally friendly coating technology. With the large-scale deployment of industrial corrosion protection, building protection, cold chain logistics, and conventional environmental facilities, the requirements for the self-healing performance of protective coatings under ambient and wide-temperature-range conditions without heating are continuously increasing. High-performance low-temperature self-healing water-based coatings have become key supporting materials for ensuring the integrity of the substrate and extending the service life of equipment. According to technical surveys in the coating industry, in ambient and near-ambient temperature applications, the application rate of protective coatings with rapid self-healing, crack resistance, wear resistance, and strong adhesion has exceeded 60%. Among these, the requirements for self-healing and comprehensive protective performance of coatings in scenarios such as metal corrosion protection, cold chain equipment, and outdoor construction account for over 75%. These coatings must simultaneously meet multiple stringent requirements, including film formation over a wide temperature range of 5~35℃, rapid self-healing at ambient temperature, strong adhesion, high wear resistance, and resistance to salt spray corrosion. However, existing self-healing waterborne coatings are limited by material systems and formulation design, making it difficult to achieve synergistic matching of multiple properties. This results in the need for additional heating to trigger repair at room temperature, poor low-temperature fluidity, low repair efficiency, and a general imbalance between flexibility and wear resistance, as well as insufficient adhesion. These issues severely restrict the industrialization of self-healing waterborne coatings under normal working conditions without heating.

[0003] To address the challenges of room temperature compatibility and performance balance in self-healing waterborne coatings, the industry has successively developed various technical approaches, including high-temperature triggered self-healing coatings, conventional epoxy-based self-healing coatings, and elastomer-modified self-healing coatings. High-temperature triggered self-healing coatings achieve fluidity and cross-linking of the repair agent through heating above 40°C, but require specific heating equipment, limiting their applicability. Furthermore, their repair efficiency at room temperature is extremely low, and microcracks cannot heal promptly. Conventional epoxy-based self-healing coatings rely on the rigidity of epoxy resin for mechanical strength, but the repair agent has high viscosity at low temperatures, poor fluidity in the 10-30°C room temperature range, and a microcrack repair rate of less than 50% within 24 hours. They also lack low-temperature flexibility and are prone to brittleness. Elastomer-modified self-healing coatings improve flexibility through elastomer toughening, but the poor compatibility between the elastomer and the resin matrix leads to phase separation, resulting in decreased coating hardness, insufficient wear resistance, and easy wear over long-term use. Moreover, the self-healing effect is easily diminished by phase separation.

[0004] To address the aforementioned technical shortcomings, there is an urgent need to improve existing technologies. Summary of the Invention

[0005] In view of this, this application provides a low-temperature self-healing waterborne coating and its preparation method. The coating has multiple core properties, including stable film formation over a wide temperature range of 5~35℃, rapid self-healing at room temperature of 10~30℃, crack resistance and flexibility, and wear and corrosion resistance. At the same time, it avoids the problems of traditional self-healing coatings, such as the need for high-temperature triggering, poor low-temperature fluidity, low repair efficiency, imbalance between flexibility and wear resistance, and insufficient adhesion. It has excellent and balanced comprehensive performance, controllable preparation process, and strong application adaptability. It is suitable for substrate protection needs in scenarios such as metal corrosion protection, building exterior walls, and cold chain equipment that require rapid repair at room temperature under no-heating conditions.

[0006] Firstly, this application provides a low-temperature self-healing water-based coating, the technical solution of which is as follows:

[0007] A low-temperature self-healing water-based coating, comprising the following components by weight:

[0008] The composition includes 50-80 parts of waterborne resin emulsion, 5-20 parts of repair microcapsules, 2-10 parts of γ-aminopropyltriethoxysilane-modified calcium carbonate, 0.1-1 parts of polycarboxylate dispersant, 0.1-0.8 parts of polyether-modified polysiloxane defoamer, 0.1-1 parts of acetylenol wetting agent, 0.1-1.5 parts of alkali-swellable acrylic thickener, 0.1-0.5 parts of polyether-modified siloxane leveling agent, 1-5 parts of low-temperature film-forming aid, and 10-30 parts of water.

[0009] Optionally, the aqueous resin emulsion is selected from one or more of aqueous polyurethane dispersions, styrene-acrylic emulsions, bisphenol A aqueous epoxy emulsions, or fluorocarbon emulsions.

[0010] Optionally, the polycarboxylate dispersant is selected from one or more of sodium polyacrylate, sodium maleate-acrylic acid copolymer, and methyl methacrylate copolymer.

[0011] Optionally, the polyether-modified polysiloxane defoamer is selected from one or more of polyether-modified dimethylsiloxane, polyether-siloxane copolymer, or fluorinated polyether-modified siloxane.

[0012] Optionally, the acetylenol wetting agent is selected from one or more of 2,4,7,9-tetramethyl-5-decyn-4,7-diol, ethoxylated 2,4,7,9-tetramethyl-5-decyn-4,7-diol, or propoxylated 2,4,7,9-tetramethyl-5-decyn-4,7-diol.

[0013] Optionally, the alkali-swellable acrylic thickener is selected from one or more of nonionic alkali-swellable thickeners, anionic alkali-swellable thickeners, or hydrophobically modified alkali-swellable thickeners.

[0014] Optionally, the polyether-modified siloxane leveling agent is selected from one or more of polyether-modified polymethylethoxysilane, polyether-modified polymethylphenylsilane, or polyether-modified organosiloxane.

[0015] Optionally, the low-temperature film-forming aid is selected from one or more of alcohol ester-12, propylene glycol methyl ether, dipropylene glycol butyl ether, or ethylene glycol butyl ether acetate.

[0016] The preparation method of the γ-aminopropyltriethoxysilane modified calcium carbonate includes the following steps:

[0017] Calcium carbonate powder and water are mixed and dispersed to obtain a calcium carbonate suspension.

[0018] γ-aminopropyltriethoxysilane and anhydrous ethanol were mixed and subjected to silane hydrolysis to obtain a modifier solution.

[0019] The modifier solution and calcium carbonate suspension were mixed and subjected to a dehydration condensation reaction to obtain γ-aminopropyltriethoxysilane modified calcium carbonate.

[0020] Optionally, the mass-to-volume ratio of the calcium carbonate powder to water is 1 g: (4~6) mL.

[0021] Optionally, the dispersion treatment is carried out under stirring conditions, wherein the stirring speed is 800~1200 r / min, the temperature is 25~35℃, and the time is 8~12 min.

[0022] Optionally, the mass-to-volume ratio of the γ-aminopropyltriethoxysilane to anhydrous ethanol is 1 g: (1.5~2.5) mL.

[0023] Optionally, the volume ratio of the modifier solution to the calcium carbonate suspension is 1:1.5~2.5.

[0024] Optionally, the silane hydrolysis reaction is carried out under stirring conditions, wherein the stirring speed is 800~1200 r / min, the temperature is 25~35℃, and the time is 15~20 min.

[0025] Optionally, the dehydration condensation reaction is carried out under stirring conditions, wherein the stirring speed is 1200~1800 r / min, the temperature is 60~70℃, and the time is 1.5~2.5 h.

[0026] Optionally, the method for preparing the repair microcapsules includes the following steps:

[0027] Polythiol oligomers, epoxy diluents and γ-glycidyl etheroxypropyltrimethoxysilane were mixed and subjected to a ring-opening addition reaction to obtain an organically modified core.

[0028] Organosilicon-modified polyurethane resin, water, and polycarboxylate dispersant are mixed and dispersed to obtain a coating solution.

[0029] The organically modified capsule core and the coating liquid are mixed and subjected to shear dispersion treatment to obtain an emulsion;

[0030] Diethylenetriamine was added to the emulsion, and cross-linking and curing treatment was performed to obtain repair microcapsules.

[0031] Optionally, the polythiol oligomer is trimethylolpropane tris(3-mercaptopropionate) or pentaerythritol tetra(3-mercaptopropionate).

[0032] Optionally, the epoxy diluent is phenyl glycidyl ether or butyl glycidyl ether.

[0033] Optionally, the mass ratio of the polythiol oligomer, epoxy diluent, and γ-glycidyl etheroxypropyltrimethoxysilane is 1:0.3~0.7:0.02~0.04.

[0034] Optionally, the mass ratio of the organosilicon-modified polyurethane resin, water, and polycarboxylate dispersant is 1g:(1.5~2.5)mL:(0.008~0.012)g.

[0035] Optionally, the mass ratio of the organically modified capsule core to the coating liquid is 1 g: (3~5) mL.

[0036] Optionally, the mass ratio of the organosilicon-modified polyurethane resin to diethylenetriamine is 1 g: (0.025~0.04) mL.

[0037] Optionally, the ring-opening addition reaction is carried out under stirring conditions, wherein the stirring speed is 600~800 r / min, the temperature is 55~65℃, and the time is 1~1.5h.

[0038] Optionally, the dispersion treatment is carried out under stirring conditions, wherein the stirring speed is 300~500 r / min, the temperature is 25~35℃, and the time is 10~15 min.

[0039] Optionally, the shear dispersion treatment is carried out under shear stirring conditions, wherein the shear stirring speed is 1800~2200 r / min, the temperature is 25~35℃, and the time is 25~35 min.

[0040] Optionally, the crosslinking curing treatment is carried out under stirring conditions, wherein the stirring speed is 800~1000 r / min, the temperature is 45~55℃, and the time is 1~1.5h.

[0041] Secondly, this application provides a method for preparing the low-temperature self-healing waterborne coating described in the aforementioned scheme, comprising the following steps:

[0042] Water, polycarboxylate dispersant and acetylation diol wetting agent are mixed and stirred to disperse, resulting in a mixed base liquid;

[0043] γ-aminopropyltriethoxysilane-modified calcium carbonate and a mixed base solution were mixed and dispersed to obtain a dispersion.

[0044] Repair microcapsules were added to the dispersion and then ground and dispersed to obtain a composite functional dispersion.

[0045] After adding aqueous resin emulsion, polyether-modified polysiloxane defoamer, alkali-swellable acrylic thickener, polyether-modified siloxane leveling agent and low-temperature film-forming aid to the composite functional dispersion, the mixture is stirred and cured in sequence to obtain a low-temperature self-healing aqueous coating.

[0046] Optionally, the stirring and dispersion treatment is carried out under stirring conditions, wherein the stirring speed is 1000~1500 r / min, the temperature is 25~35℃, and the time is 6~10 min.

[0047] Optionally, the dispersion treatment is carried out under stirring conditions, wherein the stirring speed is 1800~2200 r / min, the temperature is 10~20℃, and the time is 25~35 min.

[0048] Optionally, the grinding media for the grinding and dispersion treatment is zirconia beads, the particle size of which is 0.3~0.5mm, the time is 35~55min, and the temperature is 5~20℃.

[0049] Optionally, the stirring process is carried out under stirring conditions, wherein the stirring speed is 800~1200 r / min, the temperature is 25~35℃, and the time is 15~25 min.

[0050] Optionally, the aging process is carried out at a temperature of 5-15°C for 1.5-2.5 hours.

[0051] Thirdly, this application provides the application of the low-temperature self-healing waterborne coating described in the aforementioned scheme in the construction of protective coatings.

[0052] The low-temperature self-healing waterborne coating provided in this application is suitable for conventional environments without heating and for application within a wide temperature range of 5-35℃. It is particularly suitable for scenarios requiring rapid repair at room temperature, such as metal corrosion protection, building exterior walls, and cold chain equipment. Simultaneously, it addresses the problems of traditional self-healing coatings, including the need for high-temperature triggering, poor low-temperature fluidity, low repair efficiency, imbalance between flexibility and abrasion resistance, and insufficient adhesion and corrosion resistance. Compared to existing technologies, this low-temperature self-healing waterborne coating features rapid self-healing within a room temperature range of 10-30℃, stable film formation over a wide temperature range, crack resistance and flexibility, abrasion and corrosion resistance, and balanced overall performance. Furthermore, its preparation process is controllable, its application is highly adaptable, and it requires no additional heating equipment, demonstrating significant practicality and industrialization potential. Detailed Implementation

[0053] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, it should be understood that the specific implementation methods described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0055] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0056] In this application, "at least one" means one or more, and "more than one" means two or more. "One or more", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0057] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0058] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0059] Firstly, this application provides a low-temperature self-healing water-based coating, the technical solution of which is as follows:

[0060] A low-temperature self-healing water-based coating, comprising the following components by weight:

[0061] The composition includes 50-80 parts of waterborne resin emulsion, 5-20 parts of repair microcapsules, 2-10 parts of γ-aminopropyltriethoxysilane-modified calcium carbonate, 0.1-1 parts of polycarboxylate dispersant, 0.1-0.8 parts of polyether-modified polysiloxane defoamer, 0.1-1 parts of acetylenol wetting agent, 0.1-1.5 parts of alkali-swellable acrylic thickener, 0.1-0.5 parts of polyether-modified siloxane leveling agent, 1-5 parts of low-temperature film-forming aid, and 10-30 parts of water.

[0062] Optionally, the aqueous resin emulsion is selected from one or more of aqueous polyurethane dispersions, styrene-acrylic emulsions, bisphenol A aqueous epoxy emulsions, or fluorocarbon emulsions. These aqueous resin emulsions exhibit good low-temperature flexibility, film-forming properties, and substrate adhesion. The active groups contained in their molecular chains can form hydrogen bonds or chemical bonds with other components, thereby improving coating stability.

[0063] Optionally, the polycarboxylate dispersant is selected from one or more of sodium polyacrylate, sodium maleate-acrylic acid copolymer, and methyl methacrylate copolymer. These dispersants have good dispersing effects, enabling the γ-aminopropyltriethoxysilane-modified calcium carbonate and repair microcapsules to be uniformly dispersed in the system, avoiding uneven coating performance caused by agglomeration.

[0064] Optionally, the polyether-modified polysiloxane defoamer is selected from one or more of polyether-modified dimethylsiloxane, polyether-siloxane copolymer, or fluorinated polyether-modified siloxane. This type of defoamer can effectively eliminate bubbles generated during coating preparation and application, preventing residual bubbles from reducing the coating's density and preventing the penetration of external corrosive media.

[0065] Optionally, the acetylenol wetting agent is selected from one or more of 2,4,7,9-tetramethyl-5-decyn-4,7-diol, ethoxylated 2,4,7,9-tetramethyl-5-decyn-4,7-diol, or propoxylated 2,4,7,9-tetramethyl-5-decyn-4,7-diol. These wetting agents can reduce the surface tension of the coating, improve the wetting and spreading properties of the coating on the substrate surface, and avoid defects such as pinholes and craters.

[0066] Optionally, the alkali-swellable acrylic thickener is selected from one or more of nonionic alkali-swellable thickeners, anionic alkali-swellable thickeners, or hydrophobically modified alkali-swellable thickeners. These thickeners can adjust the viscosity of the coating to a suitable range, ensuring fluidity and stability during application and preventing sagging or uneven thickness.

[0067] Optionally, the polyether-modified siloxane leveling agent is selected from one or more of polyether-modified polymethylethoxysilane, polyether-modified polymethylphenylsilane, or polyether-modified organosiloxane. These leveling agents can promote uniform spreading of coatings on the substrate surface, improve the smoothness and gloss of the coating surface, and enhance appearance quality and protective effect.

[0068] Optionally, the low-temperature film-forming aid is selected from one or more of alcohol ester-12, propylene glycol methyl ether, dipropylene glycol butyl ether, or ethylene glycol butyl ether acetate. These film-forming aids can lower the minimum film-forming temperature of waterborne resins, ensuring normal film formation of the coating at low temperatures of 5-15°C, while simultaneously improving the continuity and density of the coating.

[0069] The preparation method of the γ-aminopropyltriethoxysilane modified calcium carbonate includes the following steps:

[0070] Calcium carbonate powder and water are mixed and dispersed to obtain a calcium carbonate suspension.

[0071] γ-aminopropyltriethoxysilane and anhydrous ethanol were mixed and subjected to silane hydrolysis to obtain a modifier solution.

[0072] The modifier solution and calcium carbonate suspension were mixed and subjected to a dehydration condensation reaction to obtain γ-aminopropyltriethoxysilane modified calcium carbonate.

[0073] Optionally, the mass-to-volume ratio of the calcium carbonate powder to water is 1 g: (4~6) mL. This ratio ensures that the calcium carbonate powder is fully dissolved and dispersed, avoids powder agglomeration, provides sufficient reaction sites for subsequent modification reactions, and ensures that the modifier is in full contact with the powder surface.

[0074] Optionally, the dispersion treatment is carried out under stirring conditions, with a stirring speed of 800~1200 r / min, a temperature of 25~35℃, and a time of 8~12 min. These process parameters can break up the initial agglomeration of calcium carbonate powder, allowing the powder to be uniformly dispersed in water, providing a uniform reaction environment for the modification reaction, and avoiding uneven modification caused by excessively high local concentrations.

[0075] Optionally, the mass-to-volume ratio of γ-aminopropyltriethoxysilane to anhydrous ethanol is 1 g : (1.5~2.5) mL. Anhydrous ethanol can effectively dissolve γ-aminopropyltriethoxysilane to form a homogeneous modifier solution. This ratio ensures that the modifier concentration is appropriate, avoiding excessive concentration leading to self-polymerization of the modifier or insufficient modification due to insufficient concentration.

[0076] Optionally, the volume ratio of the modifier solution to the calcium carbonate suspension is 1:1.5~2.5. Reasonable control of the modifier dosage can ensure full surface modification of the calcium carbonate powder, improve compatibility with the resin system, and avoid excessive dosage leading to increased costs or decreased compatibility.

[0077] Optionally, the silane hydrolysis reaction is carried out under stirring conditions, with a stirring speed of 800~1200 r / min, a temperature of 25~35℃, and a time of 15~20 min. High-speed stirring can promote the dissolution of γ-aminopropyltriethoxysilane in anhydrous ethanol, forming a stable and homogeneous modifier solution, and avoiding local aggregation of the modifier that would affect the modification effect.

[0078] Optionally, the dehydration condensation reaction is carried out under stirring conditions, with a stirring speed of 1200~1800 r / min, a temperature of 60~70℃, and a time of 1.5~2.5 h. The temperature of 60~70℃ can promote the hydrolysis of γ-aminopropyltriethoxysilane to generate silanol groups, which then undergo a condensation reaction with the hydroxyl groups on the surface of calcium carbonate to form stable chemical bonds; high-speed stirring ensures that the modification reaction proceeds uniformly, avoiding uneven performance caused by incomplete local reactions.

[0079] Optionally, the method for preparing the repair microcapsules includes the following steps:

[0080] Polythiol oligomers, epoxy diluents and γ-glycidyl etheroxypropyltrimethoxysilane were mixed and subjected to a ring-opening addition reaction to obtain an organically modified core.

[0081] Organosilicon-modified polyurethane resin, water, and polycarboxylate dispersant are mixed and dispersed to obtain a coating solution.

[0082] The organically modified capsule core and the coating liquid are mixed and subjected to shear dispersion treatment to obtain an emulsion;

[0083] Diethylenetriamine was added to the emulsion, and cross-linking and curing treatment was performed to obtain repair microcapsules.

[0084] Optionally, the polythiol oligomer is trimethylolpropane tris(3-mercaptopropionate) or pentaerythritol tetra(3-mercaptopropionate). These polythiol oligomers have multiple thiol active groups, allowing for rapid crosslinking reactions with epoxy diluents at both room and low temperatures. They also exhibit low viscosity and good flowability in the 10–30°C range, enabling them to quickly fill microcracks with a width ≤50 μm.

[0085] Optionally, the epoxy diluent is phenyl glycidyl ether or butyl glycidyl ether. This type of epoxy diluent can reduce the overall viscosity of the core, while its epoxy groups form a cross-linked network with the thiol groups of the polythiol, achieving structural stability after crack repair. It also exhibits good compatibility with the silicone-modified polyurethane core wall, preventing core leakage.

[0086] Optionally, the mass ratio of the polythiol oligomer, epoxy diluent, and γ-glycidyl etheroxypropyltrimethoxysilane is 1:0.3~0.7:0.02~0.04.

[0087] Optionally, the mass ratio of the organosilicon-modified polyurethane resin, water, and polycarboxylate dispersant is 1g:(1.5~2.5)mL:(0.008~0.012)g.

[0088] Optionally, the mass ratio of the organically modified capsule core to the coating liquid is 1 g: (3~5) mL.

[0089] Optionally, the mass ratio of the organosilicon-modified polyurethane resin to diethylenetriamine is 1 g: (0.025~0.04) mL.

[0090] Optionally, the ring-opening addition reaction is carried out under stirring conditions, wherein the stirring speed is 600~800 r / min, the temperature is 55~65℃, and the time is 1~1.5 h. These process parameters can promote the full progress of the grafting reaction, forming a structurally stable organic modified core, and avoiding uneven repair effects caused by incomplete local reactions.

[0091] Optionally, the dispersion treatment is carried out under stirring conditions, wherein the stirring speed is 300~500 r / min, the temperature is 25~35℃, and the time is 10~15 min. Low-speed stirring can achieve uniform mixing of the dispersant and the organosilicon-modified polyurethane resin, avoid the generation of bubbles by high-speed stirring that would affect the coating effect, and ensure the stability of the coating liquid system.

[0092] Optionally, the shear dispersion treatment is carried out under shear stirring conditions, wherein the shear stirring speed is 1800~2200 r / min, the temperature is 25~35℃, and the time is 25~35 min. High-speed dispersion can uniformly disperse the organic modified capsule core in the coating liquid to form an oil-in-water emulsion, laying the foundation for subsequent capsule wall solidification; the dispersion time of 25~35 min can ensure the stability of the emulsion and avoid capsule core aggregation.

[0093] Optionally, the crosslinking curing treatment is carried out under stirring conditions, wherein the stirring speed is 800~1000 r / min, the temperature is 45~55℃, and the time is 1~1.5 h. The temperature of 45~55℃ can promote the efficient curing reaction, and the stirring speed of 800~1000 r / min ensures that the capsule wall is uniformly formed during the curing process, avoiding local uneven thickness.

[0094] In this application, an aqueous resin emulsion serves as the film-forming matrix, providing excellent low-temperature flexibility and substrate adhesion. Repair microcapsules release a low-viscosity core when the coating is damaged, rapidly filling cracks and cross-linking for curing, achieving rapid self-repair in both room and low-temperature ranges. γ-aminopropyltriethoxysilane-modified calcium carbonate enhances the coating's hardness, wear resistance, and corrosion resistance through inorganic reinforcement, balancing flexibility and mechanical strength. Polycarboxylate dispersants, acetylenol wetting agents, alkali-swellable acrylic thickeners, polyether-modified siloxane leveling agents, and polyether-modified polysiloxane defoamers respectively achieve uniform component dispersion, improve substrate wetting, regulate system viscosity, optimize surface smoothness, and eliminate bubble defects. Low-temperature film-forming aids lower the resin's glass transition temperature, ensuring normal film formation in low-temperature environments. Water, as an environmentally friendly solvent, ensures uniform dispersion of all components and system stability. The above-mentioned components solve the technical problems of imbalance between film formation and crack resistance, contradiction between flexibility and wear resistance, and conflict between repair and storage in traditional low-temperature coatings. This enables the coating to have the comprehensive advantages of stable low-temperature film formation, rapid self-repair at room temperature, wear and corrosion resistance, and strong adhesion, making it suitable for the protection needs of conventional and low-temperature environments without heating.

[0095] Secondly, this application provides a method for preparing the low-temperature self-healing waterborne coating described in the aforementioned scheme, comprising the following steps:

[0096] Water, polycarboxylate dispersant and acetylation diol wetting agent are mixed and stirred to disperse, resulting in a mixed base liquid;

[0097] γ-aminopropyltriethoxysilane-modified calcium carbonate and a mixed base solution were mixed and dispersed to obtain a dispersion.

[0098] Repair microcapsules were added to the dispersion and then ground and dispersed to obtain a composite functional dispersion.

[0099] After adding aqueous resin emulsion, polyether-modified polysiloxane defoamer, alkali-swellable acrylic thickener, polyether-modified siloxane leveling agent and low-temperature film-forming aid to the composite functional dispersion, the mixture is stirred and cured in sequence to obtain a low-temperature self-healing aqueous coating.

[0100] Optionally, the stirring and dispersion treatment is carried out under stirring conditions, wherein the stirring speed is 1000~1500 r / min, the temperature is 25~35℃, and the time is 6~10 min. These process parameters allow the dispersant and wetting agent to fully dissolve in water, forming a homogeneous base liquid system, which lays the foundation for the subsequent dispersion of solid components.

[0101] Optionally, the dispersion treatment is carried out under stirring conditions, with a stirring speed of 1800~2200 r / min, a temperature of 10~20℃, and a time of 25~35 min. High-speed dispersion at 1800~2200 r / min can break the secondary agglomeration of γ-aminopropyltriethoxysilane-modified calcium carbonate, ensuring the powder is uniformly dispersed in the mixed base liquid; the temperature of 10~20℃ can prevent the volatilization of additives caused by temperature rise during dispersion, ensuring dispersion stability.

[0102] Optionally, the grinding media for the grinding and dispersion treatment is zirconia beads with a particle size of 0.3~0.5mm, a grinding time of 35~55min, and a temperature of 5~20℃. Zirconia beads have high hardness and good wear resistance, which can avoid the introduction of impurities during the grinding process; the particle size of 0.3~0.5mm can achieve uniform dispersion of microcapsules while avoiding microcapsule breakage; the low-temperature grinding at 5~20℃ can protect the microcapsule wall structure and prevent premature release of the capsule core.

[0103] Optionally, the stirring process is carried out under stirring conditions, wherein the stirring speed is 800~1200 r / min, the temperature is 25~35℃, and the time is 15~25 min. These process parameters can ensure uniform mixing of each component, avoid coating performance defects caused by excessively high local concentrations, and prevent the generation of new bubbles due to excessive stirring intensity.

[0104] Optionally, the curing treatment is carried out at a temperature of 5~15℃ for 1.5~2.5h. These process conditions can promote the interaction between the molecules of each component, improve the stability of the system, avoid microcapsule failure or premature cross-linking of the resin due to excessively high curing temperature, and ensure the storage period and performance of the coating.

[0105] Thirdly, this application provides the application of the low-temperature self-healing waterborne coating described in the aforementioned scheme in the construction of protective coatings.

[0106] It should be noted that the low-temperature self-healing water-based coating of this application is suitable for protection needs in conventional and low-temperature environments without heating. The protective coating formed after application can self-repair micro-cracks, effectively resist the erosion of external corrosive media, reduce substrate damage caused by coating failure, and extend the service life of equipment. At the same time, the coating is compatible with various coating methods, has high construction flexibility, can meet the construction needs of projects of different scales, and has mild curing conditions, requires no complicated equipment, and has low construction costs.

[0107] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0108] Example 1

[0109] This embodiment provides a method for preparing a low-temperature self-healing water-based protective coating, comprising the following steps:

[0110] Mix 18g of water, 0.3g of sodium polyacrylate, and 0.4g of ethoxylated 2,4,7,9-tetramethyl-5-decyn-4,7-diol, add the mixture to a dispersion tank, adjust the stirring speed to 1200r / min and the temperature to 30℃, and stir and disperse for 8min to obtain a mixed base liquid.

[0111] Add 4g of γ-aminopropyltriethoxysilane-modified calcium carbonate to the mixed base liquid, adjust the stirring speed to 2000r / min and the temperature to 15℃, and disperse for 30min to obtain a dispersion.

[0112] Add 8g of repair microcapsules to the dispersion, transfer to a sand mill, and grind and disperse at 2500r / min for 40min. The grinding medium is 0.4mm zirconia beads, and the temperature is controlled at 20℃ during the grinding process to obtain a composite functional dispersion.

[0113] Add 60g of waterborne polyurethane dispersion, 0.2g of polyether-modified dimethylsiloxane, 0.6g of anionic alkali-swelling thickener, 0.2g of polyether-modified polymethylethoxysilane, and 2g of alcohol ester-12 to the composite functional dispersion. Adjust the stirring speed to 1000r / min and the temperature to 30℃, and stir for 20min. Then transfer it to a curing tank and cure at 10℃ for 2h to obtain a low-temperature self-healing waterborne coating.

[0114] The preparation method of the γ-aminopropyltriethoxysilane modified calcium carbonate includes the following steps:

[0115] Mix 20g of calcium carbonate powder with 100mL of water, place the mixture in a jacketed stirring tank, adjust the speed to 1000r / min, and disperse for 10min to obtain a calcium carbonate suspension.

[0116] Mix 5g of γ-aminopropyltriethoxysilane with 10mL of anhydrous ethanol, adjust the rotation speed to 1000r / min, and hydrolyze the silane for 18min to obtain a modifier solution.

[0117] The modifier solution was mixed with 200 mL of calcium carbonate suspension, and the rotation speed was adjusted to 1500 r / min and the temperature to 65 °C. The dehydration condensation reaction was carried out for 2 h to obtain γ-aminopropyltriethoxysilane modified calcium carbonate.

[0118] The method for preparing the repair microcapsules includes the following steps:

[0119] 14g of trimethylolpropane tris(3-mercaptopropionate), 6g of phenyl glycidyl ether and 0.4g of γ-glycidyl etheroxypropyltrimethoxysilane were mixed and placed in a stirred tank. The stirring speed was adjusted to 700 r / min and the temperature to 60℃. The ring-opening addition reaction was carried out for 1.2 h to obtain the organic modified capsule core.

[0120] Mix 20g of silicone-modified polyurethane resin (solid content 30wt%) with 40mL of water, add 0.2g of sodium polyacrylate dispersant, adjust the rotation speed to 400r / min, and disperse for 12min to obtain the coating solution;

[0121] The organically modified capsule core was added to the coating solution, the rotation speed was adjusted to 2000 r / min, and the shearing and dispersion treatment was carried out for 30 min to form an emulsion;

[0122] 0.6 g of diethylenetriamine was added to the emulsion, the rotation speed was adjusted to 900 r / min and the temperature to 50 °C, and the cross-linking and curing treatment was carried out for 1.2 h to obtain repair microcapsules.

[0123] Example 2

[0124] This embodiment provides a method for preparing a low-temperature self-healing water-based protective coating, comprising the following steps:

[0125] Mix 22g of water, 0.5g of polycarboxylate copolymer dispersant, and 0.6g of 2,4,7,9-tetramethyl-5-decyn-4,7-diol, add the mixture to a dispersion tank, adjust the stirring speed to 1300r / min and the temperature to 32℃, and stir and disperse for 9min to obtain a mixed base liquid.

[0126] Add 6g of γ-aminopropyltriethoxysilane-modified calcium carbonate to the mixed base liquid, adjust the stirring speed to 2100r / min and the temperature to 18℃, and disperse for 32min to obtain a dispersion.

[0127] 12g of repair microcapsules were added to the dispersion and transferred to a sand mill. The mixture was ground and dispersed at 2800r / min for 35min. The grinding media was 0.3mm zirconia beads. The temperature was controlled at 18℃ during the grinding process to obtain a composite functional dispersion.

[0128] Add 70g of aqueous acrylic emulsion, 0.3g of polyether-siloxane copolymer, 0.8g of nonionic alkali-swelling thickener, 0.3g of polyether-modified polymethylphenylsiloxane, and 3g of propylene glycol methyl ether to the composite functional dispersion. Adjust the stirring speed to 1100r / min and the temperature to 32℃, and stir for 22min. Then transfer it to a curing tank and cure at 8℃ for 2.5h to obtain a low-temperature self-healing waterborne coating.

[0129] The preparation method of the γ-aminopropyltriethoxysilane modified calcium carbonate includes the following steps:

[0130] Mix 25g of calcium carbonate powder with 125mL of water, place the mixture in a jacketed stirring tank, adjust the speed to 1100r / min and the temperature to 32℃, and disperse for 9min to obtain a calcium carbonate suspension.

[0131] 6g of γ-aminopropyltriethoxysilane and 12mL of anhydrous ethanol were mixed, and the rotation speed was adjusted to 1100r / min and the temperature to 32℃. The silane hydrolysis reaction was carried out for 16min to obtain the modifier solution.

[0132] The modifier solution was mixed with 250 mL of calcium carbonate suspension, the rotation speed was adjusted to 1600 r / min and the temperature to 68 °C, and the dehydration condensation reaction was carried out for 1.8 h. After the reaction was completed, the mixture was filtered and dried to obtain γ-aminopropyltriethoxysilane modified calcium carbonate.

[0133] The method for preparing the repair microcapsules includes the following steps:

[0134] 12g pentaerythritol tetra(3-mercaptopropionate), 8g butyl glycidyl ether and 0.36g γ-glycidyl etheroxypropyltrimethoxysilane were mixed and placed in a stirring tank. The stirring speed was adjusted to 650r / min and the temperature to 62℃. The ring-opening addition reaction was carried out for 1.1h to obtain the organic modified capsule core.

[0135] Mix 25g of silicone-modified polyurethane resin (solid content 32wt%) with 50mL of water, add 0.25g of polycarboxylate copolymer dispersant, adjust the rotation speed to 450r / min and the temperature to 32℃, and disperse for 13min to obtain the coating solution;

[0136] The organically modified capsule core was added to the coating solution, the rotation speed was adjusted to 2100 r / min and the temperature was 32℃, and the emulsion was formed by shearing and dispersing for 28 min.

[0137] 0.8 g of diethylenetriamine was added to the emulsion, the rotation speed was adjusted to 950 r / min and the temperature to 52 °C, and the cross-linking and curing treatment was carried out for 1.1 h. After the reaction was completed, the emulsion was dried at 82 °C for 2.8 h and then sieved through a 300 mesh sieve to obtain the repair microcapsules.

[0138] Example 3

[0139] This embodiment provides a method for preparing a low-temperature self-healing water-based protective coating, comprising the following steps:

[0140] Mix 25g of water, 0.7g of polymaleic anhydride derivative dispersant, and 0.7g of propoxylated 2,4,7,9-tetramethyl-5-decyn-4,7-diol, add the mixture to a dispersion tank, adjust the stirring speed to 1400r / min and the temperature to 28℃, and stir and disperse for 7min to obtain a mixed base liquid.

[0141] 7g of γ-aminopropyltriethoxysilane-modified calcium carbonate was added to the mixed base liquid, and the stirring speed was adjusted to 2150r / min and the temperature to 12℃. The mixture was then dispersed for 33min to obtain a dispersion.

[0142] Add 15g of repair microcapsules to the dispersion, transfer it to a sand mill, and grind and disperse it at a speed of 2800r / min for 38min. The grinding medium is 0.5mm zirconia beads, and the temperature is controlled at 15℃ during the grinding process to obtain a composite functional dispersion.

[0143] Add 55g of waterborne silicone-acrylic emulsion, 0.5g of fluorinated polyether-modified siloxane, 1.0g of hydrophobic modified alkali-swelling thickener, 0.4g of polyether-modified organosiloxane, and 3.5g of dipropylene glycol butyl ether to the composite functional dispersion. Adjust the stirring speed to 1100r / min and the temperature to 28℃, and stir for 23min. Then transfer it to a curing tank and cure at 12℃ for 1.8h to obtain a low-temperature self-healing waterborne coating.

[0144] The preparation method of the γ-aminopropyltriethoxysilane modified calcium carbonate includes the following steps: 30g of calcium carbonate powder and 150mL of water are mixed and placed in a jacketed stirring tank. The rotation speed is adjusted to 1200r / min and the temperature is 33℃. The mixture is dispersed for 8min to obtain a calcium carbonate suspension.

[0145] Mix 8g of γ-aminopropyltriethoxysilane with 18mL of anhydrous ethanol, adjust the rotation speed to 1200r / min and the temperature to 33℃, and perform silane hydrolysis reaction for 15min to obtain a modifier solution.

[0146] The modifier solution was mixed with 350 mL of calcium carbonate suspension, the rotation speed was adjusted to 1700 r / min and the temperature was 68 °C, and the dehydration condensation reaction was carried out for 2.2 h. After the reaction was completed, the mixture was filtered and dried to obtain γ-aminopropyltriethoxysilane modified calcium carbonate.

[0147] The method for preparing the repair microcapsules includes the following steps: mixing 16g of trimethylolpropane tris(3-mercaptopropionate), 9g of phenyl glycidyl ether and 0.5g of γ-glycidyl etheroxypropyltrimethoxysilane, placing them in a stirring tank, adjusting the rotation speed to 750r / min and the temperature to 58℃, and performing a ring-opening addition reaction for 1.4h to obtain the organically modified capsule core;

[0148] Mix 30g of silicone-modified polyurethane resin (solid content 28wt%) with 70mL of water, add 0.3g of polymaleic anhydride derivative dispersant, adjust the rotation speed to 380r / min and the temperature to 33℃, and disperse for 14min to obtain the coating solution.

[0149] The organically modified capsule core was added to the coating solution, the rotation speed was adjusted to 1900 r / min and the temperature to 33℃, and the emulsion was formed by shearing and dispersing for 32 min.

[0150] 1.0 g of diethylenetriamine was added to the emulsion, the rotation speed was adjusted to 850 r / min and the temperature to 48 °C, and the cross-linking and curing treatment was carried out for 1.4 h. After the reaction was completed, the emulsion was dried at 78 °C for 3.2 h and then sieved through a 300 mesh sieve to obtain the repair microcapsules.

[0151] Comparative Example 1

[0152] This comparative example provides a method for preparing an aqueous protective coating, comprising the following steps:

[0153] Mix 18g of water, 0.3g of sodium polyacrylate, and 0.4g of ethoxylated 2,4,7,9-tetramethyl-5-decyn-4,7-diol, add the mixture to a dispersion tank, adjust the stirring speed to 1200r / min and the temperature to 30℃, and stir and disperse for 8min to obtain a mixed base liquid.

[0154] Add 4g of calcium carbonate to the mixed base liquid, adjust the stirring speed to 2000r / min and the temperature to 15℃, and disperse for 30min to obtain a dispersion.

[0155] Add 60g of waterborne polyurethane dispersion, 0.2g of polyether-modified dimethylsiloxane, 0.6g of anionic alkali-swellable thickener, 0.2g of polyether-modified polymethylethoxysilane, and 2g of alcohol ester-12 to the dispersion. Adjust the stirring speed to 1000r / min and the temperature to 30℃, and stir for 20min. Then transfer it to a curing tank and cure at 10℃ for 2h to obtain a low-temperature self-healing waterborne coating.

[0156] Comparative Example 2

[0157] This comparative example provides a method for preparing an aqueous protective coating, comprising the following steps:

[0158] Mix 18g of water, 0.3g of sodium polyacrylate, and 0.4g of ethoxylated 2,4,7,9-tetramethyl-5-decyn-4,7-diol, add the mixture to a dispersion tank, adjust the stirring speed to 1200r / min and the temperature to 30℃, and stir and disperse for 8min to obtain a mixed base liquid.

[0159] Add 4g of calcium carbonate to the mixed base liquid, adjust the stirring speed to 2000r / min and the temperature to 15℃, and disperse for 30min to obtain a dispersion.

[0160] Add 60g of waterborne polyurethane dispersion, 0.2g of polyether-modified dimethylsiloxane, 0.6g of anionic alkali-swellable thickener, 0.2g of polyether-modified polymethylethoxysilane, and 2g of alcohol ester-12 to the dispersion. Adjust the stirring speed to 1000r / min and the temperature to 30℃, and stir for 20min. Then transfer it to a curing tank and cure at 10℃ for 2h to obtain a low-temperature self-healing waterborne coating.

[0161] The method for preparing the repair microcapsules includes the following steps:

[0162] 14g of trimethylolpropane tris(3-mercaptopropionate), 6g of phenyl glycidyl ether and 0.4g of γ-glycidyl etheroxypropyltrimethoxysilane were mixed and placed in a stirred tank. The stirring speed was adjusted to 700 r / min and the temperature to 60℃. The ring-opening addition reaction was carried out for 1.2 h to obtain the organic modified capsule core.

[0163] Mix 20g of silicone-modified polyurethane resin (solid content 30wt%) with 40mL of water, add 0.2g of sodium polyacrylate dispersant, adjust the rotation speed to 400r / min, and disperse for 12min to obtain the coating solution;

[0164] The organically modified capsule core was added to the coating solution, the rotation speed was adjusted to 2000 r / min, and the shearing and dispersion treatment was carried out for 30 min to form an emulsion;

[0165] 0.6 g of diethylenetriamine was added to the emulsion, the rotation speed was adjusted to 900 r / min and the temperature to 50 °C, and the cross-linking and curing treatment was carried out for 1.2 h to obtain repair microcapsules.

[0166] The low-temperature self-healing waterborne coatings and protective coatings prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to coating system performance tests and coating application performance tests. The coating system performance test results are shown in Table 1, and the coating application performance test results are shown in Table 2.

[0167] The performance testing of coating systems specifically includes the following aspects:

[0168] Dispersibility: The particle size distribution of the slurry was tested using a laser particle size analyzer (test range 0.1~100μm) to observe whether there were agglomerates (particle size > 5μm is considered agglomerate).

[0169] Viscosity: measured using a rotational viscometer at 25°C for 10 seconds. -1 Test the coating viscosity at the shear rate and record the viscosity value.

[0170] Storage stability: The coating was sealed and placed in a 25°C environment, and the sedimentation was observed at 24h, 72h, and 30d (settling layer thickness > 1mm was considered unstable).

[0171] Bubble content: The volume percentage of bubbles in the coating is calculated using the hydrometer bottle method, with the formula being (theoretical density - actual density) / theoretical density × 100%.

[0172] Low-temperature film-forming properties: After the coating is applied to the substrate, it is placed in an environment of 5°C and 50% humidity, and it is observed whether a continuous, crack-free coating is formed within 24 hours.

[0173] The coating application performance test specifically includes the following aspects:

[0174] Self-healing rate: Cracks with a width of 30μm and a depth of 20μm were etched on the coating surface using a blade. The surfaces were then placed in environments of 10℃ and 35℃ for 24 hours, respectively. The crack healing was observed under a microscope. Self-healing rate = (initial crack area - residual area after healing) / initial crack area × 100%;

[0175] Hardness: Tested according to GB / T6739-2006 using the pencil hardness method, with a loading force of 1000g and a scratching speed of 5mm / s;

[0176] Adhesion: Tested according to GB / T9286-1998 using the cross-cut test (1mm grid, 6×6 grids), and observe the coating peeling at the grid edges;

[0177] Abrasion resistance: Tested using a Taber abrasion tester according to GB / T1768-2006, with a load of 500g and a rotation speed of 1000 rpm, and the amount of wear was recorded;

[0178] Salt spray resistance: Conduct a neutral salt spray test (5% NaCl solution, temperature 35℃) according to GB / T1771-2007, and observe whether the coating blisters or peels off;

[0179] Artificial aging resistance: tested using a xenon lamp (irradiance 1.5W / m²) according to GB / T1865-2009. 2 (Blackboard temperature 65℃, humidity 50%), observe the yellowing and chalking of the coating;

[0180] Low temperature stability: The coating was subjected to high and low temperature cycling tests at -20℃ to 25℃ (50 cycles, 8 hours per cycle), and the coating was observed to see if it cracked or peeled off;

[0181] Corrosion resistance: The coating was immersed in 5% H2SO4 solution and 5% NaOH solution, and the changes in the appearance of the coating were observed after 72 hours.

[0182] Table 1 Performance test results of the coating system

[0183] project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Dispersion No agglomeration, uniform particle size distribution (D90=2.8μm) No agglomeration, uniform particle size distribution (D90=2.5μm) No agglomeration, uniform particle size distribution (D90=3.2μm) Slight aggregation, with local particle size > 8 μm Severe local aggregation, with particle size >15μm <![CDATA[Viscosity (25°C, 10 s -1 )]]> 950 mPa·s 880 mPa·s 1050 mPa·s 820 mPa·s 1350 mPa·s Storage stability (24h) No settlement No settlement No settlement Slight settlement (1mm from the bottom) Significant settlement (3mm from the bottom) Storage stability (72h) No settlement No settlement No settlement Significant settlement (bottom 2.5mm) Severe settlement (6mm from the bottom) Storage stability (30 days) Slight stratification (top layer < 0.5 mm, recovers after shaking) Slight stratification (top layer < 0.5 mm, recovers after shaking) Slight stratification (top layer < 0.5 mm, recovers after shaking) Severe delamination (top layer 3mm, bottom layer 5mm) Completely separated (cannot be mixed by shaking) Bubble content ＜0.1% ＜0.1% ＜0.1% ＜0.1% 0.5%~0.8% Low-temperature film-forming properties (5℃, 24h) Continuous without cracks Continuous without cracks Continuous without cracks Localized microcracks Obvious cracks, discontinuous film formation

[0184] Table 2 Coating application performance test results

[0185] project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Self-repair rate (10℃, 24h) 78% 75% 80% - (No self-repair function) 42% (Incomplete repair) Self-repair rate (35℃, 24h) 97% 96% 98% - (No self-repair function) 65% (Incomplete repair) Pencil hardness 2H 2H 2H 1H HB Adhesion (cross-cut test) Level 0 Level 0 Level 0 Level 2 Level 3 Abrasion resistance (abrasion amount, mg) 8.2 7.8 7.5 15.6 22.3 Salt spray resistance (1500h) No bubbling, no peeling No bubbling, no peeling No bubbling, no peeling Localized blistering (area < 5%) Severe blistering (area > 30%), localized peeling Resistance to artificial aging (2500h) No yellowing (ΔE < 1.0), no chalking No yellowing (ΔE < 1.0), no chalking No yellowing (ΔE < 1.0), no chalking Slight yellowing (ΔE=2.3) Severe yellowing (ΔE=4.8), localized chalking (Grade 1) Low temperature stability (50 cycles) No cracks, no peeling No cracks, no peeling No cracks, no peeling Minor cracks (length < 5mm) Obvious cracks (length > 10mm), localized detachment <![CDATA[Acid resistance (5% H2SO4, 72 h)]]> No bubbling, no discoloration No bubbling, no discoloration No bubbling, no discoloration Slight bubbling Severe blistering, localized corrosion Alkali resistance (5% NaOH, 72h) No bubbling, no discoloration No bubbling, no discoloration No bubbling, no discoloration Localized whitening Severe whitening, edges peeling

[0186] As shown in Tables 1 and 2, the coatings of Examples 1-3 exhibit excellent dispersibility, with no agglomeration, uniform particle size distribution (D90≤3.2μm), and a viscosity ranging from 880 to 1050 mPa·s. They showed no sedimentation after 72 hours of storage and only slight stratification after 30 days, demonstrating excellent storage stability. The bubble content was <0.1%, and a continuous, crack-free coating could be formed at 5°C, indicating excellent low-temperature film-forming properties. Comparative Example 1, lacking repair microcapsules and using ordinary unmodified calcium carbonate, had poor compatibility with the resin, resulting in slight agglomeration and sedimentation, and localized microcracks during low-temperature film formation. Comparative Example 2, using ordinary water-based acrylic emulsion and unmodified calcium carbonate, showed even worse dispersion stability, with severe sedimentation after 72 hours, complete stratification after 30 days, and a bubble content as high as 0.5%~0.8%. Obvious cracks appeared during low-temperature film formation, failing to meet the requirements for low-temperature construction.

[0187] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A low-temperature self-healing water-based coating, characterized in that, By mass parts, it includes the following components: The composition includes 50-80 parts of waterborne resin emulsion, 5-20 parts of repair microcapsules, 2-10 parts of γ-aminopropyltriethoxysilane-modified calcium carbonate, 0.1-1 parts of polycarboxylate dispersant, 0.1-0.8 parts of polyether-modified polysiloxane defoamer, 0.1-1 parts of acetylenol wetting agent, 0.1-1.5 parts of alkali-swellable acrylic thickener, 0.1-0.5 parts of polyether-modified siloxane leveling agent, 1-5 parts of low-temperature film-forming aid, and 10-30 parts of water.

2. The low-temperature self-healing water-based coating according to claim 1, characterized in that, The aqueous resin emulsion is selected from one or more of the following: aqueous polyurethane dispersion, styrene-acrylic emulsion, bisphenol A aqueous epoxy emulsion, or fluorocarbon emulsion; and / or The polycarboxylate dispersant is selected from one or more of sodium polyacrylate, sodium salt of maleic acid-acrylic acid copolymer, and methyl methacrylate copolymer; and / or The polyether-modified polysiloxane defoamer is selected from one or more of polyether-modified dimethylsiloxane, polyether-siloxane copolymer, or fluorinated polyether-modified siloxane; and / or The acetylenol wetting agent is selected from one or more of 2,4,7,9-tetramethyl-5-decyn-4,7-diol, ethoxylated 2,4,7,9-tetramethyl-5-decyn-4,7-diol, or propoxylated 2,4,7,9-tetramethyl-5-decyn-4,7-diol; and / or The alkali-swellable acrylic thickener is selected from one or more of nonionic alkali-swellable thickeners, anionic alkali-swellable thickeners, or hydrophobically modified alkali-swellable thickeners; and / or The polyether-modified siloxane leveling agent is selected from one or more of polyether-modified polymethylethoxysilane, polyether-modified polymethylphenylsilane, or polyether-modified organosiloxane; and / or The low-temperature film-forming aid is selected from one or more of alcohol ester-12, propylene glycol methyl ether, dipropylene glycol butyl ether, or ethylene glycol butyl ether acetate.

3. The low-temperature self-healing water-based coating according to claim 1, characterized in that, The preparation method of the γ-aminopropyltriethoxysilane modified calcium carbonate includes the following steps: Calcium carbonate powder and water are mixed and dispersed to obtain a calcium carbonate suspension. γ-aminopropyltriethoxysilane and anhydrous ethanol were mixed and subjected to silane hydrolysis to obtain a modifier solution. The modifier solution and calcium carbonate suspension were mixed and subjected to a dehydration condensation reaction to obtain γ-aminopropyltriethoxysilane modified calcium carbonate.

4. The low-temperature self-healing water-based coating according to claim 3, characterized in that, The mass-to-volume ratio of the calcium carbonate powder to water is 1g:(4~6)mL; and / or The dispersion treatment is carried out under stirring conditions, wherein the stirring speed is 800~1200 r / min, the temperature is 25~35℃, and the time is 8~12 min; and / or The mass-to-volume ratio of the γ-aminopropyltriethoxysilane to anhydrous ethanol is 1 g : (1.5~2.5) mL; and / or The volume ratio of the modifier solution to the calcium carbonate suspension is 1:1.5~2.5; and / or The silane hydrolysis reaction is carried out under stirring conditions, wherein the stirring speed is 800~1200 r / min, the temperature is 25~35℃, and the time is 15~20 min; and / or The dehydration condensation reaction is carried out under stirring conditions, with a stirring speed of 1200~1800 r / min, a temperature of 60~70℃, and a time of 1.5~2.5 h.

5. The low-temperature self-healing water-based coating according to claim 1, characterized in that, The method for preparing the repair microcapsules includes the following steps: Polythiol oligomers, epoxy diluents and γ-glycidyl etheroxypropyltrimethoxysilane were mixed and subjected to a ring-opening addition reaction to obtain an organically modified core. Organosilicon-modified polyurethane resin, water, and polycarboxylate dispersant are mixed and dispersed to obtain a coating solution. The organically modified capsule core and the coating liquid are mixed and subjected to shear dispersion treatment to obtain an emulsion; Diethylenetriamine was added to the emulsion, and cross-linking and curing treatment was performed to obtain repair microcapsules.

6. The low-temperature self-healing water-based coating according to claim 5, characterized in that, The polythiol oligomer is trimethylolpropane tris(3-mercaptopropionate) or pentaerythritol tetra(3-mercaptopropionate); and / or The epoxy diluent is phenyl glycidyl ether or butyl glycidyl ether; and / or The mass ratio of the polythiol oligomer, epoxy diluent, and γ-glycidyl etheroxypropyltrimethoxysilane is 1:0.3~0.7:0.02~0.04; and / or The mass ratio of the organosilicon-modified polyurethane resin, water, and polycarboxylate dispersant is 1 g : (1.5~2.5) mL : (0.008~0.012) g; and / or The mass ratio of the organically modified capsule core to the coating solution is 1 g: (3~5) mL; and / or The mass ratio of the organosilicon-modified polyurethane resin to diethylenetriamine is 1 g: (0.025~0.04) mL.

7. The low-temperature self-healing water-based coating according to claim 5, characterized in that, The ring-opening addition reaction is carried out under stirring conditions, wherein the stirring speed is 600~800 r / min, the temperature is 55~65℃, and the time is 1~1.5h; and / or The dispersion treatment is carried out under stirring conditions, wherein the stirring speed is 300~500 r / min, the temperature is 25~35℃, and the time is 10~15 min; and / or The shear dispersion treatment is carried out under shear stirring conditions, wherein the shear stirring speed is 1800~2200 r / min, the temperature is 25~35℃, and the time is 25~35 min; and / or The crosslinking and curing treatment is carried out under stirring conditions, with a stirring speed of 800~1000 r / min, a temperature of 45~55℃, and a time of 1~1.5 h.

8. The method for preparing the low-temperature self-healing waterborne coating according to any one of claims 1 to 7, characterized in that, Includes the following steps: Water, polycarboxylate dispersant and acetylation diol wetting agent are mixed and stirred to disperse, resulting in a mixed base liquid; γ-aminopropyltriethoxysilane-modified calcium carbonate and a mixed base solution were mixed and dispersed to obtain a dispersion. Repair microcapsules were added to the dispersion and then ground and dispersed to obtain a composite functional dispersion. After adding aqueous resin emulsion, polyether-modified polysiloxane defoamer, alkali-swellable acrylic thickener, polyether-modified siloxane leveling agent and low-temperature film-forming aid to the composite functional dispersion, the mixture is stirred and cured in sequence to obtain a low-temperature self-healing aqueous coating.

9. The preparation method according to claim 8, characterized in that, The stirring and dispersion treatment is carried out under stirring conditions, wherein the stirring speed is 1000~1500 r / min, the temperature is 25~35℃, and the time is 6~10 min; and / or The dispersion treatment is carried out under stirring conditions, wherein the stirring speed is 1800~2200 r / min, the temperature is 10~20℃, and the time is 25~35 min; and / or The grinding and dispersion treatment uses zirconia beads as the grinding medium, the zirconia beads having a particle size of 0.3~0.5 mm, a time of 35~55 min, and a temperature of 5~20℃; and / or The stirring process is carried out under the following conditions: stirring speed is 800~1200 r / min, temperature is 25~35℃, and time is 15~25 min; and / or The aging process is carried out at a temperature of 5~15℃ for 1.5~2.5h.

10. The application of the low-temperature self-healing waterborne coating according to any one of claims 1 to 7 in the construction of protective coatings.